In an electronic device, such as a data storage device and the like, a plurality of power supply units are often used to supply power to the electronic device in need of massive power consumption. For a plurality of power supply units, there exists a situation that the supply currents of the power supply units are unbalanced. Therefore, the output power of a certain power supply unit may exceed its maximum rated output current, which can easily reduce the service life of the power supply unit. In a more severe situation, it may cause a power supply unit failure. Thus, the supply currents of the plurality of power supply units need to be balanced.